Of all rifle cartridges sold to American shooters, one of the most popular is the Federal Lake City New Unprimed Brass Rifle Cartridge Cases - .223 Rem 500/box. The primary difference between .223 and NATO-standard 5.56x45 ammo is that .223 is loaded at lower pressures.

Used primarily by the U.S. military and NATO forces who enjoy reloading, this shooting cartridge provides both efficiency and versatility. The cartridge has the ability to sling 40-grainers past 3,650 feet per second but also deliver 90-grain VLDs with incredible accuracy up to 1,000 yards. In a good rifle, the .223 is well under quarter MOA.